improve: skip unchanged manifest list images

pkg/sync/destination.go

@@ -106,17 +106,36 @@ func (i *ImageDestination) CheckManifestChanged(destManifestBytes []byte, tagOrD
 }
 
 func (i *ImageDestination) GetManifest(tagOrDigest string) []byte {
-	var err error
+	var srcRef types.ImageReference
+	var convertDigest *digest.Digest
+
+	if len(tagOrDigest) != 0 {
+		_, err := digest.Parse(tagOrDigest)
+		manifestURL := i.registry + "/" + i.repository + ":" + tagOrDigest
+		if err == nil {
+			// has digest
+			manifestURL = i.registry + "/" + i.repository + "@" + tagOrDigest
+		}
+
+		// create source to check manifest
+		srcRef, err = docker.ParseReference("//" + manifestURL)
+		if err != nil {
+			return nil
+		}
+
+		tmp := digest.Digest(tagOrDigest)
+		convertDigest = &tmp
+	} else {
+		srcRef = i.ref
+	}
 
-	// create source to check manifest
-	source, err := i.ref.NewImageSource(i.ctx, i.sysctx)
+	source, err := srcRef.NewImageSource(i.ctx, i.sysctx)
 	if err != nil {
 		// if the source cannot be created, manifest not exist
 		return nil
 	}
 
-	tDigest := digest.Digest(tagOrDigest)
-	tManifestByte, _, err := source.GetManifest(i.ctx, &tDigest)
+	tManifestByte, _, err := source.GetManifest(i.ctx, convertDigest)
 	if err != nil {
 		// if error happens, it's considered that the manifest not exist
 		return nil

pkg/sync/task.go

@@ -90,9 +90,13 @@ func (t *Task) Run() error {
 }
 
 func (t *Task) SyncListTypeImageByManifest(manifestBytes []byte, subManifestInfoSlice []*ManifestInfo) error {
-	// TODO: ignore list-type image if not changed
-	// Docker manifest list (and its tag) might still exist even it's deleted, we will always update it because we
-	// cannot make sure if it can be ignored.
+	if changed := t.destination.CheckManifestChanged(manifestBytes, ""); !changed {
+		// do nothing if manifest is unchanged
+		t.Infof("Dest manifest list %s/%s:%s is unchanged, will do nothing",
+			t.destination.GetRegistry(), t.destination.GetRepository(), t.destination.GetTag())
+		return nil
+	}
+
 	for _, mfstInfo := range subManifestInfoSlice {
 		if err := t.SyncNonListTypeImageByManifest(mfstInfo.obj, mfstInfo.bytes,
 			mfstInfo.digest.String(), mfstInfo.digest.String(), true); err != nil {
@@ -112,8 +116,8 @@ func (t *Task) SyncNonListTypeImageByManifest(manifestObj interface{}, manifestB
 	srcTagOrDigest, dstTagOrDigest string, belongsToList bool) error {
 
 	if changed := t.destination.CheckManifestChanged(manifestBytes, dstTagOrDigest); !changed {
-		// do nothing if manifest is not changed
-		t.Infof("Dest manifest %s/%s:%s is not changed, will do nothing",
+		// do nothing if manifest is unchanged
+		t.Infof("Dest manifest %s/%s:%s is unchanged, will do nothing",
 			t.destination.GetRegistry(), t.destination.GetRepository(), dstTagOrDigest)
 		return nil
 	}